Information System Development

Early information systems were designed to be operated by information professionals, and they frequently did not attain their stated social purpose. Modern information systems are increasingly used by persons who have little or no previous hands-on experience with information technology but who possess a much better perception about this technology should accomplish in their professional and personal environments. A correct understanding in their requirements, preferences, and “information styles” of these ends users is crucial to the design and success of today’s information systems.

The principle objective of the systems analysis phase is the specification of what the system is required to do. In the systems design phase such specifications are converted to a hierarchy of increasingly detailed charts that define the data required and decompose the processes to be carried out on data to a level at which they can be expressed as instructions of a computer program. The systems development phase consists of writing and testing computer software and of developing data input and out forms and conventions. Systems implementation is the installation of physical system and the activities it entails, such as the training of operators and users. Systems maintenance refers to the further evolution of the functions and structure of a system that result from changing requirements and technologies, experience with the system’s use, and fine-tuning of its performance. Many information systems are implemented with generic, “off-the-shell” software rather than with custom-built programs; versatile database management software and its nonprocedural programming languages fit the needs of small and large system alike. The development of large systems that cannot use off-the-shelf software is an expensive, time-consuming, and complex undertaking. Prototyping, an interactive session in which users confirm a system’s proposed functions and features early in the design stage, is a practice intended to raise the probability of success of such an undertaking. Some of the tools of computer-aided software engineering available to the systems analyst and designer verify the logic of the systems design, automatically generate a program code from low-level specifications, and automatically produce software and system specifications. The eventual goal of information systems engineering is to develop software that use natural language and artificial intelligence techniques as part of an integrated set of tools to support the analysis and design of large information systems.